Photon-photon interactions in Rydberg-atom arrays

We investigate the interaction of weak light fields with two-dimensional lattices atoms, in which two-photon coupling establishes conditions electromagnetically induced transparency and excites high lying atomic Rydberg states. This system features different interactions that act on disparate length scales, from zero-range defect scattering excitations finite-range dipole exchange to long-range Rydberg-state span entire array. Analyzing their interplay, we identify yield a nonlinear quantum mirror coherently splits incident into correlated photon-pairs single transverse mode, while transmitting photons unaffected. Such strong photon-photon absence otherwise detrimental photon losses Rydberg-EIT arrays opens up promising approach for generation manipulation light, exploration many-body phenomena interacting photons.